16... f7f5  17. e4f5  17... e6f5 If we remove the knight on f3 and the bishop on f5, then it becomes clear that White has an overwhelming positional advantage with his sovereign knight on d5. The presence of the light-squared bishop, however, compensates for the weakness in the pawn structure, as this bishop has remarkable mobility. 18. c2c3  18... f5g4 